# Color Theory and Light

## GA 91 — 10 August 1903, Berlin

### Lecture Seven

Matter is not dead, but something living in and of itself; and one will notice this living only when one sees it active, interacting with other matter. If one looks at a calcite crystal, one will recognize its actual nature just as little as that of a passing human being. Both must be judged in states where their innermost nature is revealed through their effects. Thus calcite placed between two flakes of tourmaline—one of which in parallel position oscillates with the light and reflects it, and the other in perpendicular position extinguishes it—will in turn influence the light oscillations by its own vibrations in such a way that regular figures in the most beautiful plays of colors are evoked in the calcite. This is based on the principle that light seen through dark appears yellow and dark seen through light appears blue. Now if light and dark alternately cover each other by vibrations in different directions and meet at their boundaries, the colors and figures come about which one has observed.

The diffraction phenomena of light are due to the same law. Light floods through space, and everything that we perceive in that space receives light and throws it back again. Only by this phenomena can we perceive individual objects. We see only that which reflects light back. Our eye receives these reflected rays which it in turn casts back upon the object which then casts its shadow, which often shows yellow and blue shades because the light from all sides outshines itself.

When the light falls through an opening into the darkroom, first a white disc appears on the opposite wall and rings of color appear all around in the penumbra. This is because at the two points of the opening the rays are intercepted and reflected back and over-radiation takes place. Onto the dark shadow environment bright light will fall and dark will shine through it as colored light. And likewise, where rays of light fall on other rays, the brighter light rays will shine through the darker polarized over-radiations and also produce colors.

Matter also has the property of changing light, and light interacting with matter produces colors. Calcite has the property of splitting the light that passes through it into double rays and changing these rays and polarizing them differently. One ray will oscillate perpendicularly to the parallel oscillations of the other, and a point seen through feldspar will appear double to the eye.

If the light passes through an object with parallel walls, no colors are produced. If it passes through an object with inclined walls, colors are produced. For example, a prism that tapers at the top will stop the rays for a shorter or longer time; and always proportionately according to the different widths of the prism, one ray will pass through earlier than the other. Due to the different time periods in the refraction, light will also alternate with dark and dark with light, and the alternation of blue and yellow in different shades will give the play of colors.

So again, for example, aniline has the property to make prismatic colors appear in a different order. This mutual influence of matter in its effects proves the living life in substance. The most diverse ether oscillations produce incessant movement in matter, and attraction and repulsion determine its behavior.